This is an application for a K23 award for Dr. Yoshio Hall, an Assistant Professor in nephrology at the University of Washington. Dr. Hall is establishing himself as a young investigator in patient-oriented clinical research of chronic kidney disease (CKD) in medically underserved populations. This K23 award will provide Dr. Hall with training and mentored research experience in the following areas: (1) recruiting and maintaining a patient cohort; (2) performing and validating diagnostic tests; (3) developing and maintaining a CKD registry from multiple data sources; (4) training in health information technology, (5) training in advanced statistical and epidemiologic methods; and (6) designing pilot intervention studies. To achieve these goals, Dr. Hall has assembled a mentoring team comprised of a primary mentor, Dr. Jonathan Himmelfarb, Director of the Kidney Research Institute and Professor of Medicine, who is recognized internationally as a leader in translational and outcomes research in persons with end-stage renal disease (ESRD) and acute kidney injury, and two co-mentors: Dr. Edward Boyko, Acting Head of the Division of General Internal Medicine at the University of Washington and former Director of the VA-funded Epidemiologic Research and Information Center, who is an internationally known investigator in the epidemiology of diabetes and obesity with extensive experience in disease registry development and management; and Dr. Glenn Chertow, Chief of Nephrology and Professor of Medicine at Stanford University, who is internationally recognized as a leader in improving care for persons with acute and chronic kidney disease . Chronic kidney disease (CKD) is an important public health problem which affects more than 26 million Americans. In the US, members of racial-ethnic minority groups and low-income populations bear a disproportionate burden of CKD, particularly ESRD. We hypothesize that the disparate rates of ESRD among these at-risk groups reflect a pattern of underutilization of care. We further hypothesize that public health systems which disproportionately care for diverse populations do not consistently identify or provide recommended care to persons with CKD who are at highest risk for progressive disease. We will test these hypotheses using a series of analyses that leverage data from (1) Harborview Medical Center, the largest public hospital system in the northwestern United States; and (2) The Community Health Network, a large safety net health system in northern California. This research will form the basis for patient-centered interventions to improve the delivery of care to diverse populations. Public health relevance: Improved understanding of local- and system-level barriers to care delivery in historically disadvantaged populations may reduce pervasive racial-ethnic and socioeconomic disparities in care and decrease the growing burden of CKD and ESRD to society.